Do you mind sharing how to add the mobile user and group? I'm also trying to access my WHS with an ATV2 thru NFS. I found and follow that guide on mediasmartserver.net. On the ATV2 I can see my WHS server when trying to add a NFS share, I can also see the my Videos folder, but can't get into the actual folder...I'm hoping your tip will fix it for me

I recommend you to take a look at this http file server. You can set up your own file server for managing and sharing files through web browser. It's like DropBox but self-hosted so that you can keep all your confidential files on your own server. The web based UI looks and feels like Windows 7 Explorer. It offers features that are not possible with a FTP server such as zipping files, downloading multiple files and folders in single download etc. It's also easier to set up and administrate than a FTP server.